1. Field of the Invention
The present invention relates to a locking device for a pole that performs a locking operation through an axial lever, and more particularly, to a locking device for a pole wherein an axial lever is disposed in the lengthwise direction of the pole to apply a clamping force to both left and right sides of upper and lower connection tubes in the radial direction, thereby requiring a relatively small operating force, increasing a locking force, and allowing fine adjustment in the locking force to be carried out.
2. Background of the Related Art
Generally, poles such as hiking poles, sports game poles, patient's walking assistant poles, and the like are used as auxiliary means for supporting a user's body. The pole is provided with a pole body and a handle connected to the end of the pole body. The pole body is generally formed by insertedly coupling a plurality of connection tubes in such a manner as to be foldable or extendable in the lengthwise direction while being kept or in use, which is called ‘telescoping pole’ or ‘antenna pole’.
A locking device for the pole is adapted to lock two neighboring connection tubes in a state where the plurality of connection tubes are extended or folded, and FIGS. 1 to 3 show a conventional lever type locking device that is capable of being operated easily by women or old people.
As shown in FIGS. 1 to 3, the conventional lever type locking device 10 is mounted on the end periphery of an upper connection tube 2 having a larger diameter than a lower connection tube 4 and has a grasping circle member 20 contracted by the manipulation of a cam lever 40 to allow the lower connection tube 4 to be fixedly clamped thereto.
The grasping circle member 20 of the locking device 10 is divided only on one side in the circumferential direction into upper and lower parts by means of an incised part 22, and the incised part 22 have extension plates 24 extended from the upper and lower portions thereof. An operating pin 30 is passed through the upper and lower extension plates 24 in such a manner as to be coupled to the cam lever 40 by means of a hinge pin 50, and the cam lever 40 has a cam face 42 formed thereon.
Referring to FIG. 3, the locking device 10 is in detail described, and if the cam lever 40 is pressed toward the grasping circle member 20, the cam face 42 is rotated to pull the operating pin 30. Thus, the upper and lower extension plates 24 are pulled to clamp the grasping circle member 20, which allows the lower connection tube 4 to be pressurized and fixed.
According to the conventional locking device 10, by the way, the cam lever 40 is rotated in the radial direction of the upper and lower connection tubes 2 and 4 and has a bent shape corresponding to the arches of the upper and lower connection tubes 2 and 4.
As a result, there is a limit in extending the whole length of the cam lever 40, which fails to exert a sufficient locking force, and further, a substantially large locking force should be needed when the locking is carried out, which really makes it for old people or women to do that. Especially, as shown in FIG. 2, pressing the end portion of the cam lever 40 does not exert its locking force sufficiently due to the relation between the end point of the cam lever 40 and the position of the hinge pin 50 and the shape of the arch of the cam lever 40. Accordingly, since the pressed portion of the cam lever 40 for locking operation 40 is formed on the intermediate portion thereof, the cam lever has a very short length operating as a lever, thereby failing to provide sufficient effects as the lever which is an important part of the lever type locking device.
Further, the grasping circle member 20 is incised only on one side thereof and is clamped only the incised side, so that the force for pressurizing the lower connection tube 4 is not applied uniformly to the entire circumferential surface of the lower connection tube 4. In addition, the arch length of the grasping circle member 20 is substantially long, so that the grasping circle member 20 is undesirably likely to be loose when pressurizing the lower connection tube 4. Accordingly, the grasping circle member 20 is not clamped strongly, thereby providing no sufficient locking force, and besides, the locking force is drastically decreased due to the repeated uses.
Moreover, as appreciated from FIG. 3, the contact point between the cam face 42 and the upper extension plate 24 when the cam lever 40 is in a locking state is far radial direction from the center of the grasping circle member 20, so that the force for pulling the upper and lower extension plates 24 is lost mostly before applied to the grasping circle member 20.